Patients with hypertrophic cardiomyopathy have abnormal electrocardiograms and a high incidence of arrhythmias. An increased incidence of sudden death has also been demonstrated which is likely to be on an arrhythmogenic basis. Body surface potential maps (BSPM) provide a non-invasive assessment of cardiac electrocal depolarizaton and recovery properties and may aid in identifying cardiac states in which ventricular arrhythmias are more likely to lead to sudden death. Body surface potential maps are generated from 192 ECG leads. A modified 32 lead system was developed as a more clinically useful system which includes all crucial information and eliminates redundancy of information. The BSPM information is stored on a floppy disc and processed at the Cardiovascular Research and Training Institute of the University of Utah. Resultant BSPM's are correlated with clinical information obtained during the in-patient work-up including two dimensional echocardiography, radionuclide cineangiography, cardiac catheterization and 24-hour ambulatory ECG monitoring in hopes of identifying patients at high risk for sudden death to allow for therapeutic intervention.